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M. Sc. Emre Babaoglu Prof. Dr. Gerhard Hilt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(41):8879-8884
An electrochemical iodine-mediated transformation of enamino-esters for the synthesis of 2H-azirine-2-carboxylates is presented. In addition, a thermic conversion of azirines to 4-carboxy-oxazoles in quantitative yield without purification was described. Both classes 2H-azirines-2-carboxylates and the 4-carboxy-oxazoles are substructures in natural products and therefore are of considerable interest for synthetic and pharmaceutical chemists. The optimization was not performed in a conventional manner with a one-factor-at-a-time process but with a Design of Experiments (DoE) approach. Beside a broad substrate scope the reaction was also employed to a robustness screen, a sensitivity assessment, and complemented with mechanistic considerations from cyclic voltammetry experiments. 相似文献
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The reaction of difluorocarbene with azirines affords a new type of azomethine ylides, viz., strained aziriniodifluoromethanides. 1,3-Dipolar cycloadditions of ylides derived from 2-unsubstituted 3-arylazirines to dimethyl acetylenedicarboxylate and aldehydes give derivatives of 2,2-difluoro-1-azabicyclo[3.1.0]hex-3-ene-3,4-dicarboxylic acids and 1,4-oxazin-3(4H)-ones, respectively. Ylides derived from 2-mono- and 2,2-disubstituted azirines undergo isomerization to 2-aza-1,3-diene derivatives. 2,2-Difluoro-1-azabicyclo[3.1.0]hex-3-enes are transformed into 2-fluoropyridine derivatives in high yields and react with amines to give 2,4-diamino-1-azabicyclo[3.1.0]hex-2-ene derivatives. 相似文献
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Yun‐Zhou Zhao Hai‐Bin Yang Prof. Dr. Xiang‐Ying Tang Prof. Dr. Min Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(9):3562-3566
RhII‐catalyzed intermolecular [3+2] cycloaddition of 2 H‐azirines with N‐sulfonyl‐1,2,3‐triazoles is disclosed, in which a series of fully functionalized pyrroles is produced via rhodium azavinyl carbene intermediates. A distinct feature of this reaction is that the azavinyl carbene serves as a [2 C] equivalent, instead of as [1 C] or aza‐[3 C] synthons, which have been reported previously in cyclopropanations and [3+n] cycloadditions. Moreover, this methodology has also been successfully applied in the total synthesis of URB447 as well as the formal synthesis of Atorvastatin (Lipitor). 相似文献
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Ong SY Zhu P Leung KH Phillips DL 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(6):1377-1386
We report time-resolved resonance Raman spectra for the azirine intermediate produced in the 2-fluorenylnitrene ring-expansion reaction to form a dehydroazepine product. The Raman bands obtained with a 252.7 nm probe wavelength and 500 ns delay time exhibit reasonable agreement with predicted vibrational frequencies from density functional calculations for two isomers of azirine intermediates that may be formed from a 2-fluorenylnitrene precursor. The Raman bands observed for delay times of 15 ns and 10 micros were consistent with predicted vibrational frequencies from density functional calculations for the 2-fluorenylnitrene and dehydroazepine product species as well as previously reported 416 nm time-resolved Raman spectra obtained on the ns and micros time scales. Our results demonstrate that the 2-fluorenylnitrene ring-expansion reaction to produce dehydroazepine products proceeds via relatively long-lived 2-fluorenylnitrene and azirine intermediates. Substitution of a phenyl ring para to the nitrene group of phenylnitrene appears to lead to significant changes in the ring-expansion reaction so that longer lived arylnitrene and azirine intermediates can be observed. This should enable the chemical reactivity of azirine intermediates formed from arylnitrenes to be examined more readily. 相似文献
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